Theorem 1.2 ([1]}, Theorem 6.1) 
Let \(r, s, t\)  be nonzero integers with \(r+s+t=0\) , and let \(A\subset \mathbb {Z}\)  have \(d^*(A)>0\) . Then \(rA+sA+tA:=\lbrace ra_1+sa_2+ta_3: a_i\in A\rbrace \)  contains a Bohr neighborhood of 0, with rank and radius depending only on \(r, s, t\) , and \(d^*(A)\) .

